HFSP3 Block Diagram for the lowest cost system

A good next step in development is to create a minimal core system comprised of all the basic essential elements. This step is intended to provide the lowest cost working system. The advanced control system will expand on this basic core.


There are three blocks in this system. The block on the left provides T/R switching and the DC/DC Converter (24VDC 8A) to the Amp Module. The 95% efficient PS is controlled by a PIC (used in HF PackerAmp V4). When the amp is off, the standby power is very low. The PIC is asleep (very quiet) unless made awake by RF Input or PTT control. The PIC controls the T/R switching and optional fan.

The Middle Block is the 100W Amp Module. It is powered by the 24V DC/DC Converter. The design does not subject you to low battery problems as in traditional 12V systems. The higher drain voltage is only present during transmit. Currents are lower in this design. Manual control allows you to set the max RF Input to match your transceiver in 1dB steps (1–15dB). All RF cabling uses quality SMA connections and cables. The bias is set to 1A per MOSFET (active only in transmit).  A mv shunt makes measurement and setting simple. The Amp Module is attached to the heat sink and case mounting plate. This approach  modularizes the packaging.

The Right side block diagram is the Low Pass filter covering 10 HF Bands 160–10M using a manual 6–position band switch. This is a continuous duty 100W LP Filter. Relays on input and output provide excellent isolation.

It is my intent to get this going quick as possible and make it available. The automated system adds a control element for auto band switching, amp control, more features and adds a touch screen display. 

I have not concerned myself with the final packaging other than to make every element modular. I do not foresee a stacking board package arrangement but rather a side-by-side approach. The case for this core system will be simple but functional.

I am starting with 24VDC drain voltage but the PSU can be configured for 48V 5A if a higher drain voltage is beneficial.

Thank you for your continued support!

73, K5OOR –  Virgil

HF Projects





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